How can you say the number seems low? You dont know the boost, the turbo (not all 30r's are the same)other mods, fuel, etc. You have no way to make that judgment. Also, it's on a mustang dyno, which always reads low.

seems like maybe some fuel mods? 339 seems kinda low for a 30r but i don't know the new evox motors, a 30r in a 4g63 is a different story

what other mods besides the 30r